Mahler 9 is my favourite piece, I am glad that one more person has just discovered this precious treasure in the world of music.
Which lib do you borrow the discs from? Seems to me quite interesting and rare versions, and I only have Emil Tabakov's.
Noted recordings include:
Bruno Walter / Vienna Philharmonic
Otto Klemperer / New Philharmonia
Herbert von Karajan / Berlin Philharmonic (1982)
Gary Bertini / Kolner Rundfunk-Sinfonieorchester
Claudio Abbado / Gustav Mahler Jugendorchester
Riccardo Chailly / Royal Concertgehouw Orchestra
Daniel Barenboim / Staatskappelle Berlin
Personally I prefer Bertini and Barenboim. Bertini's rendition is profound and Barenboim's is smooth.